/*
 * Copyright (C) 2011-2013 Markus Junginger, greenrobot (http://greenrobot.de)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.mlizhi.base.dao.query;

import android.database.sqlite.SQLiteDatabase;
import com.mlizhi.base.dao.AbstractDao;

/**
 * A repeatable query for deleting entities.<br/>
 * New API note: this is more likely to change.
 * 
 * @author Markus
 * 
 * @param <T>
 *The enitity class the query will delete from.
 */
public class DeleteQuery<T> extends AbstractQuery<T> {
private final static class QueryData<T2> extends AbstractQueryData<T2, DeleteQuery<T2>> {

private QueryData(AbstractDao<T2, ?> dao, String sql, String[] initialValues) {
super(dao, sql, initialValues);
}

@Override
protected DeleteQuery<T2> createQuery() {
return new DeleteQuery<T2>(this, dao, sql, initialValues.clone());
}
}

static <T2> DeleteQuery<T2> create(AbstractDao<T2, ?> dao, String sql, Object[] initialValues) {
QueryData<T2> queryData = new QueryData<T2>(dao, sql, toStringArray(initialValues));
return queryData.forCurrentThread();
}

private final QueryData<T> queryData;

private DeleteQuery(QueryData<T> queryData, AbstractDao<T, ?> dao, String sql, String[] initialValues) {
super(dao, sql, initialValues);
this.queryData = queryData;
}

public DeleteQuery<T> forCurrentThread() {
return queryData.forCurrentThread(this);
}

/**
 * Deletes all matching entities without detaching them from the identity scope (aka session/cache). Note that this
 * method may lead to stale entity objects in the session cache. Stale entities may be returned when loaded by their
 * primary key, but not using queries.
 */
public void executeDeleteWithoutDetachingEntities() {
checkThread();
SQLiteDatabase db = dao.getDatabase();
if (db.isDbLockedByCurrentThread()) {
dao.getDatabase().execSQL(sql, parameters);
} else {
// Do TX to acquire a connection before locking this to avoid deadlocks
// Locking order as described in AbstractDao
db.beginTransaction();
try {
dao.getDatabase().execSQL(sql, parameters);
db.setTransactionSuccessful();
} finally {
db.endTransaction();
}
}
}

}
